Counterbalanced crane



S. T. SJOBERG.

COUN-TERBALANCED CRANE.

APPLICATION FILED 056.26, 1919.

1,344,659. Patented June 29,1920.

2 SHEETS-SHEET I.

.s.- SJOBERG.

COUNTERBALANCED CRANE. APPLICATION FILED DEC.26, 1919- 1,344,659. vPatented June 29,1920.

2 SHEETS-SHEET 2.

6 'aef/rg AZ (23 M UNITED STATES PATENT OFF-ICE.'

SIDNEY '1. SJ'OBERG, OF CHICAGO, ILLINOIS, ASSIGNOR TO WHITING FOUNDRYEQUIPMENT COMPANY, OF HARVEY, ILLINOIS, A CORPORATION OF ILLI- NOIS.

COUNTERBALANCED CRANE.

Specification of Letters Patent.

Patented June 29, 1920.

Application filed December 26, 1919. Serial No.- 347,355.

To'aZZ whom it may concern:

Be it known that I, SIDNEY T. SJOBERG, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Counterbalanced Cranes,of which the following is a specification.

This invention relates to lifting cranes of the jib type.

The object of the invention is to provide an automatic counterbalancingmechanism for a jib crane particularly when mounted on a truck or otherloose support to take care of the load so that the load will notoverturn. Another object is to provide such mechanism in which thecounterweight, while swinging in unison with the jib is always above thewheel supports of the truck so that it can never interfere with movementof the loaded truck.

The invention consists in mechanism for carrying out the foregoingobjects which can be easily and comparatively cheaply made, which issatisfactory in operation, and not readily liable to get out of order.More in detail, the invention consists in means for simultaneouslylifting and supporting the jib of the crane and a counter weighttherefor 011 the opposite side of the crane mast in such manner as toentirely prevent friction at the mast itself and for doing this by thesame operating mechanism which normally lifts the load out at the end ofthe jib of the crane. More particularly, the invention consists infeatures and details of construction hereafter more fully set forth inthe specification and claims.

Referring to the drawings in which like numerals represent the sameparts,

Figure 1 is a side view of a jib crane so constructed as to illustratethis invention in its preferred form. v

Fig. 2 is a detail plan view on the line 22 of Fig. 1, showing twoalternative constructions of shaft mounting.

Fig. 3 is an end view of the machine taken on the irregular line 3-3 ofFig. 1.

The mechanism of this invention is perfectly applicable to a stationarycrane with its mast rising from a fixed point in the floor and some ofthe claims are drawn to that scope but it is especially applicable tobeing mounted on a truck 10 carried by wheels 12 traveling either ontheground or floor or, if desired, on rails 13.

Suitably supported, in the particular case here illustrated, on thetruck 10, is an uprlght mast 14'having at its base a pivot pin or bolt16, near whose opposite ends are ournaled, in the usual manner, thespaced side members of the jib boom 18 adapted to swing up and down onthe right side of the mast. Similarly pivoted on a shaft 16, butextending to the opposite side of the mast 14, are members constitutingthe counterweight arm 20 carrying at its outer end the counterweightproper 22 designed to balance the jib 18 and some load and to swing upand down on the left side of the mast.

The mast is conventionally carried by frame 26 and braced thereto by theangular member 24. The mast and frame, as illustrated, are rotatable ona vertical pivot 27 in thefranie 10. T he mast itself is a metal columnmade up of two oppositely disposed channel members 14, Fig. 1, or 14,Fig. 2. Channel 14 is perforated in an elongated vertical slot 28reinforced by angle irons 30. Channel 14 shows an alternativeconstruction in which a vertical passageway'29, corresponding infunction to slot 28, is provided between angle irons 30 attached to theinside of channel 14, the channel itself being unperforated. Enteringand sliding in the oppositeguiding slots 28 or passages 29, accordingtowhich construction is used, is a vertically reciprocatable shaft 32,pivotally supported on oppositely disposed. bars 34 and 36 connectedrespectively to the jib 18 at pivot 38 and to the counterweight arm 20at pivot 40. Figs. 1 and 3 show these bars outside the mast, while in.the alternative construction of Fig. 2 they are inside the mast. It isobvious that if, with only the parts thus far described, jib 18 wereforced upward, the bar or bars 34 would tend to force shaft 32'upward,thus carrying the counterweight with it through the enforced action ofbar 36, and it is further obvious that there would probably be so muchfriction between the shaft 32 and the sides of guiding passages 28 and29 that no'move ment at all would be permitted.

The mechanism for lifting the outer end of jib 18, and consequently theload carried thereby, comprises a pull bar 42 pivoted to the end of thejib at l l, carrying on its inner end a rotatable pulley L6 and a ropeconnection 52. Attached to this connection 52 is a rope 4-8 which passesfirst around pulley 54 on bracket 56; thence around pulley 4:6; thenceagain over the top of pulley 54:; thence down the mast to and aroundpulley 60; thence up the mast to winding drum 62, mounted near the topof the mast, and driven through the gearing 66 and wheels 68 by theusual chains 70, without novelty in the art.

From the foregoing, it will be seen that as chain 70 and consequentlygearing mechanism 68-(36 is operated to wind the rope onto drum 62, thevery first result is to tighten the rope around drum or pulley 60, andthus lift it vertically upward. This movement supports shaft 32 on thelifting rope with the result first that the shaft is practically clearat the sides of guiding passages 28 or 29, thereby reducing, if notentirely eliminating, friction at that point, this because this movementtends to lift the jib through rods 3st and the counter-weight through;rods 36. Further lifting movement of the rope acts through the reductionpulleys d6-5t to powerfully lift the outer end of the jib at pin 44-.

As in all cranes of this type, the load to be lifted is suspended on ahook 72 on the end of a rope 74 passing over a pulley 76 on the end ofthe jib and manipulated by mechanism 78 of conventional form, with outnovelty, carried by the crane on the platform 26 or otherwise. The loadis lifted by this mechanism independently of movement of the jib andload by chains 70 as heretofore described.

The result of the fore oin construction is that the counterweight 22moves up and down automatically with the jib 1S and load thereon therebyholding the center of gravity of the loaded crane inside the truckwheels 12 thus preventing the trucks tipping over or in the case ofstationary column relievin the strain on the foundation bolts. Kndfurthermore, this movement of the counterweight takes place practicallywithout friction along the mast guides 28 or 29 as the case may be.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent, is

1. In mechanism of the class described, an upright mast, a jib pivotedto one side thereof, a counterweight mechanism pivoted to the other sidethereof, a member slidable vertically of the mast, means connecting saidslidable member to the jib and the counterweight respectively and meansfor moving said slidable member along the mast to simultaneously movethe jib and counterweight.

2. In mechanism of the class described,

an upright mast, a jib pivoted to one side thereof, a counterweightmechanism pivoted to the other side thereof, a member necting saidslidable member to the jib and the counterweight respectively and meanssuspending the slidable member and attached parts practically clear ofthe mast and for elevating them up the mast.

4. In mechanism of the class described, an upright mast, a jib pivotedto one side thereof, a counterweight mechanism pivoted to the other sidethereof, a member slidable vertically of the mast, means connecting saidslidable member to the jib and i the counterweight respectively andmanually operated means suspending the slidable member and attachedparts practically clear of the mast and for elevating them up the mast.

5. In mechanism of the class described, an upright mast, a memberslidable up and down said mast, ajib pivoted to the mast to swing on oneside thereof, a counterweight mechanism pivoted to the mast to swing onthe other side thereof; supporting devices connecting the memberreciprocatable in the mast to the jib and to the counterweight mechanismrespectively, a lifting mechanism for the jib connected at approximatelyits} outer end, and means operated by said lifting mechanism for movingthe member reciprocatable in the mast, in unison with the jib.

6. In mechanism of the class described, a suitable support, a jibpivoted thereto, swinging in a vertical plane on one side thereof, acounterweight pivoted to the support, swinging in the same verticalplane on the other side thereof, means operatively connecting the jiband counterweight to move in unison, means for lifting the outer end ofthe jib and means operated by the same lifting means for simultaneouslylifting the counterweight, and the jib at a point intermediate betweenits ends.

7. In mechanism of the class described, a vertical mast made fromoppositely disposed separated members, a shaft slidable vertically inguides on said separated members, a pulley on said shaft between saidmembers, a jib pivoted to said mast to swing in a vertical plane on oneside thereof, a supporting rod mechanism connecting said jibintermediate between its ends to said shaft, a counterweight armmechanism pivoted to the mast, to swing in a vertical plane on theopposite side of the mast from the jib, a rod supporting mechanismbetween the counterweight support and said shaft, a load liftingmechanism located above said shaft consisting of a flexible memberpassing from a power operating device to the outer end of the jib, andmeans whereby said flexible power member on its way to the outer end ofthe jib passes around said pulley on the shaft and thereby supports andmoves the previously mentioned devices connecting said shaft to thecounterweight mechanism and the jib respectively.

In witness whereof, I have hereunto subscribed my name in the presenceof two witnesses.

SIDNEY T. SJOBERG. Witnesses DWIGHT B. OI-IEEVER, ANNA RosENTHAL.

